Risk homeostasis theory, utility and accident loss in a simulated driving task

The suggestion that utility is logically necessary for behavioural adjustments to be made in response to changes in intrinsic risk is fundamental to risk homeostasis theory (RHT). However, the methodology used to investigate RHT — analysis of road traffic accidents — is ill-suited to the investigation of this assertion. The role of utility and intrinsic risk as possible determinants of behavioural compensation were therefore examined experimentally across 14 specific behaviours using the Aston Driving Simulator. RHT predicts that these two factors act in a multiplicative way to form a statistical interaction. It also predicts that the behavioural pathways through which the effect manifests itself should be reconcilable with the concept of utility. Both predictions received little support in this experiment, suggesting that utility and intrinsic risk operate as independent factors: both factors produced significant main effects across a number of behaviours. This finding, if it can be generalised, implies that, contrary to mathematically-based models of danger compensation and the traditional model of risk homeostasis, utility is not logically necessary for behavioural compensation in response to a change in intrinsic risk.     

Method for determining minimum pool requirements to maintain and enhance salmonid fisheries in small Wyoming reservoirs

Methods for determination of minimum pool levels in reservoirs that consider sport fishery values are being sought by managers. We developed a technique for assessing the effects of incremental changes in minimum pool levels on potential salmonid abundance in small (<100 surface hectares at full pool) reservoirs in Wyoming managed for irrigation and municipal water supplies. The method has two components. One component is used to determine the minimum pool level needed to eliminate the risk of overwinter loss of salmonids due to low dissolved oxygen concentrations. The other component predicts the potential biomass of salmonids in reservoirs as a function of water depth and total dissolved solids concentration of the reservoir water. Application of the method is demonstrated for two reservoirs in Wyoming. The unit is jointly supported by the University of Wyoming, the Wyoming Game and Fish Department, and the US Fish and Wildlife Service.     

Use of sequential extraction to assess the influence of sewage sludge amendment on metal mobility in Chilean soils

In Chile, the increasing number of plants for the treatment of wastewater has brought about an increase in the generation of sludge. One way of sludge disposal is its application on land; this, however involves some problems, some of them being heavy metal accumulation and the increase in organic matter and other components from sewage sludge which may change the distribution and mobility of heavy metals. The purpose of the present study was to determine the effect of sewage sludge application on the distribution of Cr, Ni, Cu, Zn and Pb in agricultural soils in Chile. Three different soils, two Mollisols and one Alfisol, were sampled from an agricultural area in Central Chile. The soils were treated with sewage sludge at the rates of 0 and 30 ton ha(-1), and were incubated at 25 degrees C for 45 days. Before and after incubation, the soils were sequentially extracted to obtain labile (exchangeable and sodium acetate-soluble), potentially labile (soluble in moderately reducing conditions, K4P2O7-soluble and soluble in reducing conditions) and inert (soluble in strong acid oxidizing conditions) fractions. A two-level factored design was used to assess the effect of sludge application rate, incubation time and their interaction on the mobility of the elements under study. Among the metals determined in the sludge, zinc has the highest concentration. However, with the exception of Ni, the total content of metals was lower than the recommended limit values in sewage sludge as stated by Chilean regulations. Although 23% of zinc in sludge was in more mobile forms, the residual fraction of all metals was the predominant form in soils and sludge. The content of zinc only was significantly increased in two of the soils by sewage sludge application. On the other hand, with the exception of copper, the metals were redistributed in the first four fractions of amended soils. The effect of sludge application rate, incubation time and their interaction depended on the metal or soil type. In most cases an increase in more mobile forms of metals in soils was observed as the final effect.     

Performance evaluation of a biotrickling filter treating a mixture of oxygenated VOCs during intermittent loading

Laboratory scale-studies on the biodegradation of a 1:1:1 weight mixture of three oxygenated volatile organic compounds (VOCs), ethanol, ethyl acetate, and methyl-ethyl ketone (MEK) in a biotrickling filter (BTF) were carried out using two identically sized columns, filled with different polypropylene rings. The performance of the BTFs was examined for a period of 10 months applying several operational strategies. Similar performance was obtained for both supports. Intermittent flow rate of trickling liquid was shown beneficial to improve the removal efficiency (RE). Continuous feeding of VOC resulted in an excessive accumulation of biomass so high pressure drop was developed in less than 20-30 d of operation. Intermittent VOC loading with night and weekend feed cut-off periods passing dry air, but without addition of water, was shown as a successful operational mode to control the thickness of the biofilm. In this case, operation at high inlet loads (ILs) was extended for more than 75 d maintaining high REs and low pressure drops. Outlet emission concentrations lower than 100 mg Cm(-3) were obtained for ILs up to 100 g Cm(-3)h(-1) working at 15s of empty bed residence time. The most easily biodegradable compounds ethanol and ethyl acetate were used primarily than MEK. After a 3-wk-starvation period, the system performance was almost restored since the first d of operation, being the removal of the less biodegradable compound, MEK, partially deteriorated.     

Biofilms coating Schoenoplectus californicus as indicators of water quality in the Río de la Plata Estuary (Argentina)

N-ethyl-3-carbazolecarboxaldehyde-3-thio- semicarbazone (ECCT) as an new analytical reagent used for the development of a highly sensitive extractive spectrophotometric method for the determination of copper(II). The ECCT forms a greenish-yellow colored 1:1 (M:L) complex with copper(II) at pH 3.0, which is well extracted into n-butanol and shows maximum absorbance at 380nm. The color of the complex is stable for more than forty eight hours. The system obey Beer's law in the range 0.4–3.6 with 2.243 × 10⁴lmol⁻¹cm⁻¹, 2.83 × 10^-3μgcm⁻² molar absorptivity and Sandell's sensitivity respectively. The regression coefficient is 0.412 with 0.99 correlation coefficient. The precision and accuracy of the method was checked by finding the relative standard deviation (0.422%). This developed method has been successfully employed for the determination of copper(II) in environmental and pharmaceutical samples. The method is evaluated by analyzing samples from the bureau of analyzed samples (BCS 233, 266, 216/1, 207 and 179) and by inter comparison of experimental values using AAS.     

Application of manure and compost to contaminated soils and its effect on zinc accumulation by Solanum nigrum inoculated with arbuscular mycorrhizal fungi

Zn accumulation in Solanum nigrum grown in naturally contaminated soil in the presence of different types of organic amendments was assessed. Under the same conditions, the response of the plant to inoculation with two different isolates of arbuscular mycorrhizal fungi (AMF) (Glomus claroideum and Glomus intraradices) was also evaluated. S. nigrum grown in the non-amended soil always presented higher Zn accumulation in the tissues, with the addition of amendments inducing reductions of up to 80 and 40%, for manure and compost, respectively, and enhancing plant biomass yields. The establishment of S. nigrum in the Zn contaminated soil combined with the application of amendments led to a 70-80% reduction in the amount of Zn leached through the soil. The use of S. nigrum in combination with manure appeared as an effective method for reducing the effects of soil contamination, diminishing Zn transfer to other environmental compartments via percolation.     

EDDS and EDTA-enhanced zinc accumulation by Solanum nigrum inoculated with arbuscular mycorrhizal fungi grown in contaminated soil

The effect of two different chelating agents [EDTA and EDDS (S,S-ethylenediaminedissucinic acid)] on Zn tissue accumulation in Solanum nigrum L. grown in a naturally contaminated soil was assessed. Under those conditions, the response of the plant to the inoculation with two different isolates of arbuscular mycorrhizal fungi (AMF)--Glomus claroideum and Glomus intraradices--was also studied. Plants grown in the local contaminated soil (Zn levels of 433mg kg(-1)) accumulated up to 1191mg kg(-1) of Zn in the roots, 3747mg kg(-1) in the stems and 3409mg kg(-1) in the leaves. S. nigrum plants grown in the same soil spiked with extra Zn (Zn levels of 964mg kg(-1)) accumulated up to 4735, 8267 and 7948mg Zn kg(-1) in the leaves, stems and roots, respectively. The addition of EDTA promoted an increase in the concentration of Zn accumulated by S. nigrum of up to 231% in the leaves, 93% in the stems and 81% in the roots, while EDDS application enhanced the accumulation in leaves, stems and roots up to 140, 124 and 104%, respectively. In the stems, the presence of Zn was predominantly detected in the cortex collenchyma cells, the starch sheath and the internal phloem and xylem parenchyma, and the addition of chelating agents did not seem to have an effect on the localisation of accumulation sites. The devise of a chelate-enhanced phytoextraction strategy, using chelating agents and AMF, is discussed.     

The Power of Innovation and Strategic Sustainability Positioning: A Survey of the Mining Sector in Brazil

This study investigates the relationship between the power of innovation and the sustainability strategies of companies involved in the minerals extraction sector in Brazil. The study included companies associated with the Brazilian Mining Institute, and it used research surveys to gather data. Analysis of the survey data revealed that companies with highly intensive characteristics in regard to innovation and environmental activities (environmental management activities) also display offensive, or proactive, strategies for pursuing sustainability.